In engineering, especially in vehicle safety engineering, explosive studs are employed as actuator units. As a rule, they are extremely robust metal parts that are fastened by a thread and are capable of absorbing excessive forces. The required activating energy of these explosive studs is correspondingly high so that they expose housing orifices, displace component parts (sometimes against a pressing force) or cut themselves in two, for instance.
In the case of modern vehicle safety systems, especially in the case of airbag modules, it is endeavored to adapt the safety system more individually to different parameters of a crash situation. It is a known and advantageous possibility to make use of tensile means such as, e.g., tethers, by release of which flow orifices are opened or closed. Moreover, by such tensile means also the airbag geometry can be influenced and/or an additional airbag volume can be released.
For the active release of a tether a so-called tether activation unit “TAU” is required. Such TAU are usually stressed for shearing by comparatively small shear force loads. Conventional explosive studs are frequently oversized and too expensive for these applications.
For this reason, in WO 2007/065715 A1 for actuating a vehicle safety system pyrotechnic actuator units are disclosed already which have a plastic case and can be cheaply manufactured.
In WO 2007/065709 A1 furthermore an airbag module comprising an actuator unit in the form of a TAU is described in which a retaining means is provided to restrict the free mobility of a fragment separated after activation of the actuator unit. In this way, undesired contact with a vehicle occupant or damage of the airbag module by the separated fragment is largely excluded.
It is the object of the invention to provide a cheap and easily manufactured actuator subassembly that meets all safety requirements made to pyrotechnic actuators as regards movable components or fragments and at the same time can be easily mounted in a vehicle safety system